/*
 * Copyright 2004-2011 H2 Group.
 * Copyright 2011 James Moger.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.iciql;

import com.iciql.util.Utils;

/**
 * This class provides static methods that represents common SQL functions.
 */
public class Function implements Token {

    // must be a new instance
    private static final Long COUNT_STAR = new Long(0);

    protected Object[] x;
    private String name;

    protected Function(String name, Object... x) {
        this.name = name;
        this.x = x;
    }

    public <T> void appendSQL(SQLStatement stat, Query<T> query) {
        stat.appendSQL(name).appendSQL("(");
        int i = 0;
        for (Object o : x) {
            if (i++ > 0) {
                stat.appendSQL(",");
            }
            query.appendSQL(stat, null, o);
        }
        stat.appendSQL(")");
    }

    public static Long count() {
        return COUNT_STAR;
    }

    public static Integer length(Object x) {
        return Db.registerToken(Utils.newObject(Integer.class), new Function("LENGTH", x));
    }

    @SuppressWarnings("unchecked")
    public static <T extends Number> T sum(T x) {
        return (T) Db.registerToken(Utils.newObject(x.getClass()), new Function("SUM", x));
    }

    public static Long count(Object x) {
        return Db.registerToken(Utils.newObject(Long.class), new Function("COUNT", x));
    }

    public static Boolean isNull(Object x) {
        return Db.registerToken(Utils.newObject(Boolean.class), new Function("", x) {
            public <T> void appendSQL(SQLStatement stat, Query<T> query) {
                query.appendSQL(stat, null, x[0]);
                stat.appendSQL(" IS NULL");
            }
        });
    }

    public static Boolean isNotNull(Object x) {
        return Db.registerToken(Utils.newObject(Boolean.class), new Function("", x) {
            public <T> void appendSQL(SQLStatement stat, Query<T> query) {
                query.appendSQL(stat, null, x[0]);
                stat.appendSQL(" IS NOT NULL");
            }
        });
    }

    public static Boolean not(Boolean x) {
        return Db.registerToken(Utils.newObject(Boolean.class), new Function("", x) {
            public <T> void appendSQL(SQLStatement stat, Query<T> query) {
                stat.appendSQL("NOT ");
                query.appendSQL(stat, null, x[0]);
            }
        });
    }

    public static Boolean or(Boolean... x) {
        return Db.registerToken(Utils.newObject(Boolean.class), new Function("", (Object[]) x) {
            public <T> void appendSQL(SQLStatement stat, Query<T> query) {
                int i = 0;
                for (Object o : x) {
                    if (i++ > 0) {
                        stat.appendSQL(" OR ");
                    }
                    query.appendSQL(stat, null, o);
                }
            }
        });
    }

    public static Boolean and(Boolean... x) {
        return Db.registerToken(Utils.newObject(Boolean.class), new Function("", (Object[]) x) {
            public <T> void appendSQL(SQLStatement stat, Query<T> query) {
                int i = 0;
                for (Object o : x) {
                    if (i++ > 0) {
                        stat.appendSQL(" AND ");
                    }
                    query.appendSQL(stat, null, o);
                }
            }
        });
    }

    @SuppressWarnings("unchecked")
    public static <X> X min(X x) {
        Class<X> clazz = (Class<X>) x.getClass();
        X o = Utils.newObject(clazz);
        return Db.registerToken(o, new Function("MIN", x));
    }

    @SuppressWarnings("unchecked")
    public static <X> X max(X x) {
        Class<X> clazz = (Class<X>) x.getClass();
        X o = Utils.newObject(clazz);
        return Db.registerToken(o, new Function("MAX", x));
    }

    public static Boolean like(String x, String pattern) {
        Boolean o = Utils.newObject(Boolean.class);
        return Db.registerToken(o, new Function("LIKE", x, pattern) {
            public <T> void appendSQL(SQLStatement stat, Query<T> query) {
                stat.appendSQL("(");
                query.appendSQL(stat, null, x[0]);
                stat.appendSQL(" LIKE ");
                query.appendSQL(stat, x[0], x[1]);
                stat.appendSQL(")");
            }
        });
    }

}
